In electronic devices, resonators have been used as devices for realizing a timekeeping function. Recently, with the reduction in the sizes of electronic devices, there has been a demand for a reduction in the sizes of resonators, and resonators that are manufactured by using micro-electromechanical systems (MEMS) technology (hereinafter referred to as MEMS resonators) have attracted attention.
In a MEMS resonator, the frequency of the MEMS resonator will vary as a result of the mass and the shape of a vibration arm varying in accordance with variations in etching time and in the concentration of an etching liquid. Consequently, there is a need to suppress such frequency variations.
Patent Document 1 (identified below) discloses a configuration for a resonator in which frequency variations that occur due to the influence of etching are suppressed in a bending-vibration-type resonator that causes a plurality of vibration arms to perform bending vibration.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-180173.
In the configuration described in Patent Document 1, by forming a recess at an end portion of each of the vibration arms, an increase in the frequency with a reduction in the mass of the end portions of the vibration arms and a decrease in the frequency with a reduction in the widths of the vibration arms cancel each other out such that the frequency variations are suppressed.
However, in the configuration in which the recesses are formed at the end portions of the vibration arms, the strength of each of the vibration arms decreases.